A prosthesis of this type comprises an envelope made of a flexible material which is inert from a biological point of view, and in particular is made of silicone, which envelope defines a closed pocket containing in its interior physiological serum consisting of hydrogel or silicone gel with variable cohesiveness. The prosthesis thus has a flexible and malleable nature, which, once it has been fitted, allows it to imitate the appearance and habitual deformations of a natural breast.
The permanent breast prostheses which are sold at present have a major disadvantage, i.e. once they have been fitted, their content (liquid or gel) tends to “drop” downwards and to agglutinate in the lower part of the pocket. Consequently, the upper part of the envelope, on the front side, tends to fold or wrinkle since it is no longer maintained or supported in the interior by the prosthetic content (liquid or gel), as the latter has migrated downwards. The person who is wearing the prosthesis can then have an appearance of folds or “waves”, particularly in the top part of the skin of the breast, which firstly is unattractive, and secondly has the effect of indicating to other people that she is wearing a prosthesis.